Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A : If the average kinetic energy of $\text{H}_2$ and $\text{O}_2$ molecules, kept in two different sized containers are same, then their temperatures will be same.
Reason R : The r.m.s speed of $\text{H}_2$ and $\text{O}_2$ molecules are same at same temperature.
Choose the correct answer from the options given below
Answer: (C) A is true but $\mathbf{R}$ is false
The average translational kinetic energy of a molecule is $\dfrac{3}{2}k_BT$, which depends only on temperature, so equal average KE means equal temperature. A is true.
$v_{\text{rms}} = \sqrt{\dfrac{3RT}{M}}$ depends on molar mass, so at the same temperature hydrogen molecules move $4$ times faster than oxygen molecules. R is false.
Solution by Sreeraj P, M.Sc Physics